Optical recording, and particularly magneto-optical recording for providing rewritable data file storage systems provides high-density, high-capacity file memories. To record information on a disk of a magneto-optical recording system, an external magnetic field is used to apply a binary code magnetization force to the disk while a laser beam of about 1 .mu.m in diameter is used to apply localized heat to the region concerned and thereby establish the recording of the binary code.
Methods of recording binary code data by laser beam include the mark position recording method and the mark length recording method To record the data "010010", for example, with the mark position recording method, a mark is applied with the laser beam at the center of the data is and the space between two marks, corresponding to two 1s, is regarded as data 0s. With the mark length recording method, on the other hand, at the occurrence of the first 1, the laser beam is used to form the leading edge of a mark at the center part thereof and then form the trailing edge at the center part of the next contiguous 1. When the next 1 is reached, the leading edge is again formed at the center thereof and the recording method is repeated. Thus, the portions between the leading and trailing edges are treated as data 0s.
The emphasis in development of magneto-optical recording systems is focused on increasing the recording capacity and providing an overwrite capability to improve the data transfer rate. To improve the linear recording density, in particular, various techniques have been used with the mark position recording method, such as (1) forming fine magnetic domains, (2) using MCAV (Modified Constant Angular Velocity), which provides a constant disk recording density, (3) using short wavelength light sources, and (4) reducing the track pitch.
Since the mark length recording method utilizes the edges of marks, it has the advantage of enabling higher densities than the mark position recording method. On the other hand, the mark length recording method requires precise control in the length and width of the recording domains, which are effected by variations in the temperature of the environment in which the system is operating.
JP-A-Hei 3-22223 describes a method directed at providing high-precision control of the magnetic domains. In this method, a series of pulse trains are formed that correspond to the length of recording code trains, in which the recording code train length, amplitude and pulse width are controlled in accordance with the length of the reverse phase recording code string that immediately precedes the recording code train. However, it has been difficult to apply such control techniques to the mark length recording method.
With respect to achieving higher recording density, the mark length recording method is more advantageous than the mark position recording method, although the above-described disadvantages regarding precise control of the length and width of the recording domains has made the mark length recording method difficult to implement.